Brazing or heat treating furnace



y 1962 H. E. MESCHER ETAL 3,035,819

BRAZING OR HEAT TREATING FURNACE 4 Sheets-Sheet 1 Filed June 5, 1961INVENTORS HAROLD E. MESCHER WALTER E. HEYER y 2, 1962 H. E. MESCHER EIAL3,035,819

BRAZING OR HEAT TREATING FURNACE Filed June 5, 1961 4 Sheets-SheetINVENTORS HAROLD E MESCHER WALTERE.HEYER BY #W W' ATTORNEY y 1962 H. E.MESCHER ETAL 3,035,819

BRAZING OR HEAT TREATING FURNACE Filed June 5, 1961 4 Sheets-Sheet 3FIG.3 I5

INVENTORS HAROLD E. MESCHER WALTER E. HEYER ATTORNEY May 22, 1962 H E.MESCHER ETAL 3,035,819

BRAZING OR HEAT TREATING FURNACE Filed June 5, 1961 4 Sheets-Sheet 4 1ill! I I I i t 1 2O HAROLD E. MESCHER WALTER E. HEYER A TORNEY UnitedStates Patent Ghtice 3,335,319 Patented May 22, 1962 3,035,319 BRAZINGOR HEAT TREATING FURNACE Harold E. Mescher, Los Angeles County, andWalter E.

Heyer, Orange County, Calif., assignors to Pacific Scientific Company,Los Angeles, Calif., a corporation of California Filed June 5, 1961,Ser. No. 114,782 7 Claims. (Cl. 257-303) This invention relatesgenerally to furnaces for brazing and/ or heat treating work andequipment, such as rocket motors, and the invention has reference moreparticularly to a novel furnace of the above character especiallysuitable for reliably brazing complicated equipment quickly and withgreat case.

One object of the present invention is to provide a novel furnace of theabove character that employs a common base for both heating and cooling,such base being stationary and not requiring any handling of the work inpassing from the heating to the cooling cycles.

Another object of the present invention is to provide a novel furnace ofthe above character so constructed and designed as to facilitate theconvenient and rapid heating of Work or equipment to be brazed or heattreated, the maintenance of a desired operating temperature, and therapid cooling of the treated equipment or work after the heating cycleis over, without the necessity of moving the work or equipment treatedat any time during the complete cycle of operation.

Another object of the present invention is to provide a novel furnace ofthe above character that employs relatively movable mating shells orsections for effecting the heating and cooling of the equipment or workbeing treated.

A feature of the present invention is the provision of heating shellshaving unique low heat storage insulating wall surfaces for rapidlyrising to and maintaining the desired temperature within the furnaceduring treatment and employing uniformly distributed effectiveflat-plane heaters for facilitating rapid heating of the same in use.

Another feature of the present invention is the provision of matingcooling shells or sections having cold walls which rapidly absorb heatdue to radiation and high temperature differentials, the cold walls alsoabsorbing great heat due to convection through the use of large air flowpassing therewithin.

Still another feature of the present invention is the provision of novelsealing and locking means whereby, when the heating sections or shellsare closed, the combustion within the shells can be controlled at willwith- FIG. 1 is a perspective view of the novel furnace of thisinvention shown in open position and with treated equipment, such as arocket motor enclosed Within a sealed retort about to be removed fromthe same;

FIG. 1A is a fragmentary view of a portion of the structure of FIG. 1showing the sealing of the lower portion of a heating chamber section;

FIG. 2 is a view in side elevation of the cooling chamber with itsshells in closed and locked position;

FIG. 3 is a view, similar to FIG. 2, of the heating chamber, showing itstwo shells or sections in closed, locked position;

PEG. 4- is an enlarged fragmentary view illustrating one form of thesealing and locking mechanism of the heating chamber;

FIG. 5 is a view taken along line 55 of FIG. 4 looking in the directionof the arrows;

FIG. 6 is a sectional view taken along the line 66 of P16. 5 looking inthe direction of the arrows; and

FIG. 7 is a fragmentary view illustrating a modified form of sealingmeans.

Similar characters of reference are used in the above figures todesignate corresponding parts.

Referring now to the drawings, reference numeral 1 designates astationary platform or base having the form of a grating of the novelfurnace of this invention, upon which base is adapted to be placed aclosed retort 2 containing work such as a rocket motor to be brazed orheat treated. In the drawings, the furnace is illustrated as receivingretort 2 which is of large size since the furnace is capable of beingmade in almost any size desired. Mounted upon a floor 1' are pairs oftracks 3 and 4 which are shown crossing each other at right angles, andthe base or work area 1 is common or at the intersection of both pairsof tracks. Mounted upon the tracks 3 for movement therealong are wheeledcarriages 5 and 5', the said carriages carrying similar and opposedcomplementary heating chamber sections or shells 6 and 6'. Thesesections 6 and 6, mounted upon the carriages 5 and 5, are adapted totraverse the tracks 3 so as to move toward or away from each other bymeans of electric motor drives 7 and 7, which drives are controlled inoperation from a console 8 used in conjunction with control panel 9under the control of an operator 10 who is sufficiently removed from thefurnace to be protected from the great heat thereof, but, nevertheless,can see fully the operation of the furnace.

The shells or sections 6 and 6' are shown as of substantiallysemi-cylindrical shape and comprise metal exterior side and top wallshaving an interior lining 11 of lightweight, highly refractoryinsulating material that has an extremely low heat absorptioncoefficient, and hence is highly effective even though used in arelatively thin light layer: a suitable material for this purpose beingFiberfrax, a product of the Carborundum Company. This lightweightinsulating material covers the inner side and top walls of sections 6and 6. Distributed throughout the inner semi-cylindrical side wallsurfaces of each of the heating sections 6 are flat-flame, high-heatrelease gas burners or heating elements 12, the distribution of theseelements being such that, as illustrated in the figures, a substantiallycomplete envelope of heat is provided all over the inner cylindricalwall surface of the heating chamber when the sections 6, 6' are broughttogether, as shown in FIG. 3, while in use. These uniformly distributedburners, acting in conjunction with the low heat storage refractory 11,produce an enclosure in use of almost uniform radiant heat releasewhereby the hot face of the high insulating low heat storage material 11follows the heat source in temperature very closely and, in doing so,becomes a secondary source of heat by reradiating the heat from the basesource inwardly toward the retort 2, effectively heating uniformly andrapidly all portions of the work contained therewithin, enabling thefurnace to have a rapid heating cycle in use.

The side edges of the heating sections 6 and 6' are shown provided withI-beams 13 and 13' attached thereto and extending vertically, the beams13 of shell 6 opposing the beams 13' of shell 6' when these shells arebrought together. Attached to the opposed faces of the I-beams are shownstrips of sealing material, such as treated asbestos 14 and 14', whichstrips abut each other in sealing relation when the shells are broughttogether in use, thereby preventing the escape of hot exhaust gases fromthe heating chamber and allowing the heating chamher to have a readilycontrolled temperature. In those bustion from the heating chamber.

sections 6 and 6' are brought together preparatory to a instances wherethe heating chamber is of large size this form of sealing means shown inFIG. 7 is preferred. In this form of the invention the sealing strips36, as of graphited asbestos engaging one of the I-beams such as 13',are carried by leaf springs 37 mounted on the other I-beam, such as 13,which springs act to urge the strips 36 into uniform contact with thebeam 13 all along its length, regardless of any distortion of thisI-beam. Plates 39 cover adjoining portions of adjacent longitudinallyarranged springs 37 to prevent the escape of hot gases from betweenadjacent springs 37.

The retort 2 is shown supported above base 1 by means of struts 35 sothat furnace heat can pass readily under the retort 2 for uniformheating in use, as will further appear. A controlled atmosphere ofdesired pressure,

. such as argon, nitrogen and hydrogen, in any sequence desired can bemaintained within closed retort 2 as by use of gas feed pipes 37entering the bottom of this retort (see FIG. 1A).

The top walls 15 and 15' of the casing 6 and 6' are shown provided withcomplementary flue openings 16 and 16' to enable the regulated escape ofthe products of combustion. Also, flues 38 connect with the lowerportions of the heating chamber sections 6 and 6' to allow the regulatedescape of combustion products in use.

Mounted on the I-beams 13 in mutually vertically spaced relation are aseries of pneumatic cylinders 17 (see also FIG. 4) which have pistonmovable plungers 18 projecting therefrom, the outer ends of whichplungers are enlarged to form cylindrical locking heads 19 having outertapered portions 20. The heads 19 are adapted I 21 have lower reducedportions 24, the peripheries of which are adapted to engage theundersurface of heads A 19 when the slide bars 22 are moved upwardly bymeans of rods 25 driven by pistons within pneumatic cylinders 26 mountedon heating section 6'.

Thus, when the two shells 6 and 6' are initially brought together, therods 25 will hold the slide bars 22 in their lower positions, as shownin FIG. 5, so that the locking heads 19 will pass through apertures 21.Thereafter, the cylinders 26 are excited to force rods 25 upwardly, andhence slide bars 22 upwardly, to cause the narrow portions 24 ofapertures 21 to engage behind the locking heads 19. The cylinders 17 canthen be energized to hold the heads 19 firmly against the slide bars 22to firmly compress the sealing material 14 and 14' between I- beams 13and 13', or in the case of FIG. 7, to hold the sealing material 36firmly against I-beam 13', thereby tightly sealing the two sections orshells 6 together and preventing the undesired escape of the products ofcorn- After the heating 7 pending knife blades for engaging in the sandseals and 41. Thus, gases of combustion cannot escape around theperiphery of the base 1, so that a desired temperature can be maintainedwithin the combustion chamber in use.

Thus, with the heating sections closed, the retort 2 and its containedwork can be raised in a very short time to a brazing temperature throughuse of the effective flatflame burners 12 which surround the retort. Inpractice, a rocket motor weighing approximately six tons and standingmany feet high can be brought up to brazing temperature in one hour in adesired atmosphere, brazed for a period of thirty minutes and cooled to400 F. within a short time thereafter, so that the entire heating cycleof a large piece of work of this nature takes but a short time. Sincethe atmosphere within the retort 2 can be closely controlled and nooxidation takes place, the parts remain bright and clean brazing takesplace. The same highly efiicient operation can take place if a heattreatment operation is desired.

The cooling is effected by moving the shells 6 and 6 apart from eachother through operation of the motors 7 and 7 from the console 8, andthe cooling shells or sections 28 and 28' are brought together intoclosed position as shown in FIG. 2. These cooling sections are alsoshown of semi-cylindrical shape but open at their upper and lower endsso that air can be driven upwardly through the same, as by means of ablower 29 located beneath the base (see FIG. 3). The cooling shells 28and 28' are also supported upon movable carriages 30 and 36' similar tocarriages 5 and 5, the carriages 3i} and 3t) riding on track 4. Theshells 28 and 2.8 have water supply lines 34, 34 for supplying coolingwater to water conducting spray tubes 33 and 33' at their upper ends forspraying cooling water on the outer wall surfaces of these shells sothat in use the cooling water sprayed on the walls of shells 28 and 28together with the air blast from blower 29 and auxiliary blowers 31mounted on the carriages 30 and 30' produces a terrific swirling of airwithin the closed cooling chamber sections, resulting in rapid coolingof the retort and the work therein. This rapid cooling is desirable inorder to initially set the braze rapidly and to quickly pass through thecritical range of alloys used so as to prevent weld cracks, and it mustbe borne in mind that the cold wall chamber sections 28 and 28 readilyabsorb heat radiated from the work and carry this heat away through thecirculating water. Rapid circulation of air within the cooling sectionsor shells 28 and 28' in use also effects rapid cooling. These shells maybe held together when the cooling chambers are being used by use ofpneumatic cylinders 17 and locking heads 19 as described in connectionwith the heating chamber sections.

After the cooling cycle is over, the sections 28 and 28' can be readilymoved apart through operation of motors 32 and 32 from console 8,whereupon the work can be lifted away as by use of a crane preparatoryto the insertion of new work into the furnace.

Thus, it will be seen that the novel furnace of the present inventionprovides for the rapid, efiicient heating of the work, the maintenanceof uniform temperature within the heating chamber 6, 6' and controlledatmosphere within the retort 2, obtaining uniform brazing or heattreating as the case may be, the quick separation of the two sections orcasing halves 6 and 6' upon the completion of the heating cycle, therapid closure of the cooling sections 28 and 28', and then thetremendously rapid cooling afforded by the chilled wall areas of thesecasings and by the tremendous blast of air which circulates within thesame during the cooling cycle. Thus, the novel furnace of the presentinvention provides an exceedingly efficient cycle of operations enablinga rapid cycle with thorough heat treatment or brazing of work of anysize and eliminating any handling of the work during the entire cycle ofoperations, resulting in a uniform product. Since all operations takeplace by remote control from the console 8, injury to personnel inoperating the furnace is eliminated.

Since many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. A furnace of the character described comprising a stationary base forreceiving a retort containing work to be treated, pairs of tracksintersecting at the periphery of said base, complementarycarriage-supported heating chamber sections movable over one pair ofsaid tracks, motor means for moving said heating chamber sections towardeach other to enclose the work upon said base, heating elements carriedby said heating chamber sections for effecting the heating of the retortand contained work to the desired temperature within said closedsections and the maintenance of the work at such temperature until thework has been treated, said motor means serving to move said heatingchamber sections away from each other and from the Work after theheating operation, complementary carriage-supported cooling chambersections movable over another pair of said tracks, additional motormeans for moving said cooling chamber sections toward each other toenclose the work after the operating cycle to quickly cool the same,said additional motor means serving to move said cooling chambersections away from each other and away from the Work after the coolingoperation, whereupon the work may be removed from said base.

2. A furnace as defined in claim 1 wherein said heating chamber sectionsare interiorly covered with a lightweight, highly insulating, low-heatabsorbing lining, said heating elements comprising flat-plane burnersdistributed over the interior surfaces of said heating chamber sectionsand acting to substantially uniformly heat said lining, whereby thelatter acts as a radiant heater to effectively and uniformly heat theretort and contained work.

3. A furnace as defined in claim 2 wherein said heating chamber sectionsare of substantially semi-cylindrical shape and are provided withsealing material at their meeting edges whereby the products ofcombustion are prevented from escaping from said sections when they arein closed abutting position.

4. A furnace as defined in claim 3 wherein leaf springs are providedalong the meeting edges of said heating chamber sections for pressingthe sealing material uniformly against at least one of said sections toobtain a tight seal.

5. A furnace as defined in claim 3 wherein remotely controlled lockingmeans are provided for locking said heating chamber sections togetherwhen in closed position.

6. A furnace as defined in claim 1 wherein said cooling chamber sectionsare of substantially semi-cylindrical shape and are water-cooled toprovide an effective radiant heat sink, and means for circulatingcooling fluid within said closed cooling chamber sections and outwardlythereof to effect rapid convection cooling of the work.

7. A furnace having cruciform tracks enclosing a heating area adapted toreceive work to be treated, complementary heat insulated heating shellsmovable over one of said tracks for enclosing the work, heating elementswithin said shells to quickly heat the work to the desired operatingtemperature and to maintain the same at such temperature during theheating operation, and complementary cooling shells movable over theother of said tracks for enclosing the work, said cooling shells havingcooling fluid circulating over the walls thereof, and throughout theinterior thereof to absorb heat from the Work by convection and radiantabsorption, to thereby rapidly cool the work whereupon said coolingshells are movable apart to allow the work to be removed.

Albert Oct. 28, 1952 Grunewald et a1. Oct. 25, 1955

